Mechanical frequency up-conversion for sub-resonance, low frequency vibration harvesting

This article presents analysis and model validation of a single cantilever frequency up-conversion mechanism under stochastic excitation when configured as an electromagnetic energy harvester. The results show that the mechanism is able to achieve an increase in the root mean square velocity of the cantilever end when excited at frequencies below the natural frequency of the beam in the range of 3–7 Hz, as compared to a simple cantilever. The maximum observed gains in root mean square velocity from the experiment varied from 69% at a fundamental excitation frequency of 7 Hz to 153% at 3 Hz for cantilevers with natural frequencies in the range of 8.5–13.3 Hz as compared to a simple cantilever device with the same range of natural frequency. Comparison between the experimental and simulation results demonstrates that the mathematical model of the mechanical system is able to predict the response under such excitation conditions with 99% of the points in the parameter space being fitted at the 95% confidence...